He suggests residents go over their earthquake plans with their families.
'We live in earthquake country so we should do all the things they tell us to do,' Knudsen said.
#earthquake,' a Twitter user with the name @Troop206Oakland wrote in a message, as the social media service lit up with comments, many light-hearted.
About an hour after the quake, San Francisco´s Department of Emergency Management sent a text to residents saying there was no tsunami warning.
The Hayward fault, attached to the larger San Andreas fault system, is one of the most feared in the Bay Area because it can produce a magnitude 7 or greater earthquake and it runs right though heavily populated towns.
The USGS calls the fault a 'tectonic time bomb' which could 'cause hundreds of deaths, leave thousands homeless and devastate the region's economy'.
An earthquake shook California's San Francisco Bay Area early on Thursday, waking many, but there were no immediate reports of damage. Its epicenter was in Berkeley, across the bay from San Francisco, but was felt up to 40 miles away.
Its simply the cell phone number of a single individuals who wants to have some fun by sending sexts back and forth.
East Bay residents are being warned to look out for aftershocks, which can happen days and weeks after a quake.
But there's also a chance that this was a foreshock, a precursor to a larger earthquake.
Thirty people died then and there was extensive damage.
The trouble now though is that the population along the fault is 100 times larger, with an estimated two million people living directly on top of it.